1. Field of the Invention
This invention relates to water tight sealing between the concrete walls of septic tanks and like subterranean concrete vessels, and pipes Which pass through the walls for carrying effluent therethrough. More specifically it relates to the design of a seal which is embedded in the concrete wall during casting of the concrete wall, that seals against any one of a variety of septic pipes that are used in the trade, including straight walled, corrugated, and schedule 40 pipe and which reversibly fastens the seal in the mold of the concrete wall during casting of the wall.
2. Description of the Prior Art
U.S. Pat. No. 4,103,901, patented Aug. 1, 1978, by J. Ditcher, describes an assembly which is described here as seen in cross section, in order, from the periphery toward the center of an annulus of flexible elastomeric material. It is a radially oriented T with a bulbous bottom end, followed by a first oblique leg extending beyond one side of center line, followed by a reverse angled second oblique leg which crosses back to the other side of center line, ending in a bulbous termination. The bulbous termination is an O-ring which grips the pipe that is inserted through the seal. The T with bulbous bottom end is fully embedded in the concrete. Because the O-ring has little latitude for expansion and may resist insertion of the pipe, a temporary lubricated nose cone of frustoconical shape is sometimes placed on the pipe before it is inserted through the O-ring. If the pipe is smaller than the O-ring, a stainless steel tension band may be placed over the second oblique leg to clamp it around the pipe.
The ring is cast into the concrete wall peripheral to the opening through the wall to a depth in which the wall encloses the T and bulbous bottom end. For the casting procedure, the assembly is sandwiched between the smaller diameter ends of two frustoconical mold rings. The mold rings are held together on the assembly by an axially oriented slotted bracket that extends from a first spanning strap on one ring, and passes through the O-ring and through a slot in a second spanning strap on the other mold ring. The bracket is pinned in the second strap by a cross pin or key through the slot in the bracket.
U.S. Pat. No. 4,333,662, patented Jun. 8, 1982 by W. D. Jones, describes an annulus of flexible elastomeric material which is described here as seen in cross section, taken in the direction from a hollow ring in sealing contact with the pipe, toward the outer radial periphery of the seal assembly. It is the hollow ring, a short radial connector leg, attached to a pyramidal base with surfaces that diverge at a dihedral angle of about 140 degrees relative to one another. The diverging elastomeric surfaces protect the pipe from being damaged by the concrete surface of the opening. The lower portion of the base is cast into the concrete which forms the opening through the wall. Additional legs extend, one from each side of the base, and cover the remaining concrete on the inward facing surface of the opening through the wall. Each leg then folds back inward in a V, where the outer leg of the V is also cast in the concrete.
The seal is held during casting, by a pair of disks which sandwich the hollow ring between them, their shoulders resting against the diverging elastomeric surfaces and the legs. The disks are drawn together in parallel relationship by a pattern of axial bolts through them.
U.S. Pat. No. 5,286,040, patented Feb. 15, 1994 by N. W. Gavin, describes an annulus of flexible elastomeric material comprising an outer cylindrical wall that fits within the opening in the concrete housing and has a radially outward extending element embedded in the concrete during the casting of the concrete housing. The outer cylindrical wall further has an inward depending, frustoconical wall. The smaller diameter end of the frustoconical wall seals against the pipe. A diaphragm attached to the annular edge of the smaller diameter end and sealing, over the smaller diameter end has different diameter tear out rings so that various size openings can be made at the smaller diameter end to seal around various diameter pipes. In casting the seal in the concrete wall of the housing, the seal is mounted by the frustoconical wall of the seal, on a frustoconical plug which is mounted on a movable portion of the wall of the mold. Axially extending pins on the diaphragm engage the smaller diameter face of the frustoconical plug and align the seal about the axis of the cylindrical wall in a preferred rotational position.
U.S. Pat. No. 4,951,914, patented Aug. 28, 1990 by Meyers et al., describes an annulus of flexible elastomeric material comprising an outer cylindrical wall that fits within an opening in a wall of a concrete housing and has a radially outward extending element embedded in the concrete during the casting of the concrete wall of the housing. The outer cylindrical wall has an inward depending, frustoconical wiper attached by the larger diameter end to one end of the cylindrical wall. The smaller diameter end of the frustoconical wiper extends into the cylinder and seals against the pipe.
In casting the seal in the wall, a frustoconical plastic mandrel bolted on a swing out portion of the mold wall seats in the frustoconical wiper of the seal. The mandrel has, at the radially outward edge of the smaller diameter end, a gripper portion which releasibly frictionally retains the free end of the frustoconical wiper wall from one side during casting of the seal assembly in the concrete wall of the housing. An annular knock out plug or plate, rests against the smaller diameter end of the mandrel within the confines of the outer cylindrical wall in order to prevent entry of liquid concrete into the space between the outer cylindrical wall and the frustoconical wiper.